Characteristics

Defense

Poison-type Pokémon are immune to being poisoned (except by a Pokémon with Corrosion), and a grounded Poison-type Pokémon automatically removes Toxic Spikes on its side when it switches in. Although the majority of non-Poison types are able to learn Toxic, as of Generation VI, when a Poison-type uses the move, it cannot miss, bypassing accuracy checks and semi-invulnerable turns from moves such as Fly and Dig.

Offense

Poison-type moves, including the damaging moves, usually are capable of inflicting poison or bad poison. Poison-type attacks pair well with Ground, which covers Rock, Poison, and Steel-type Pokémon while Poison covers Grass.

Contest properties

In Contests, Poison-type moves typically become Clever moves. None of them are considered Cute.

Pokémon

As of Generation VII, there are 66 Poison-type Pokémon or 8.2% of all Pokémon, making it the 8th most common type.

In the TCG

Due to the decreased amount of types in the TCG, Poison-type Pokémon were generally listed as Grass Pokémon until the Diamond & Pearl set, but they have since been moved to being a part of the Psychic-type.

Poison-type Pokémon in the TCG are generally weak to Psychic Pokémon and they have no resistances. They were strong against Fighting and Water Pokémon prior to Diamond & Pearl, now however they are strong against the Grass, Fighting and Psychic types. They can be resisted by Colorless and Darkness, as well as Metal Pokémon since the Diamond and Pearl expansion set.

Trivia

Generation I introduced the most Poison-type Pokémon of any generation, with 33, and Generation VI introduced the fewest Poison-type Pokémon, with two.

As of Generation VII, half of the Pokémon that have the Poison-type were introduced in Generation I.

Generation I introduced the most Poison-type moves of any generation, with eight, and Generation II introduced the fewest Poison-type moves, with only one.

In Generation I, the Poison type is super effective against Bug-type Pokémon, while the Bug type is super effective against Poison-type Pokémon. As such, this was the only pair of types to ever be super effective against each other.